Buying a home in San Diego? Learn what to know about coastal ADU rules before purchasing a property near the coast.
An open backyard or detached garage can make a coastal property look like a good candidate for an accessory dwelling unit. However, available space alone doesn’t determine whether an ADU can be built.
If you’re buying a home in San Diego with plans to add an ADU, first determine which rules apply to the exact parcel, what type of unit you want, and whether the property can physically support the project.
Which zoning and overlay rules apply to the property?
Start by checking the home’s base zoning and whether it falls within the Coastal Overlay Zone. Other designations may also affect the project, including the Beach Impact Area, a historic district, environmentally sensitive land, or a parking impact area.
San Diego generally allows ADUs in zones that permit residential use, but coastal ADU rules may add further requirements. A project that appears possible on a similar property elsewhere in the city may not be permitted on the coastal parcel you’re considering.
What type of ADU are you planning?
“Adding an ADU” can mean several different things. A buyer might want to:
- Convert part of the existing home
- Convert a garage or accessory structure
- Build an attached addition
- Construct a new detached unit
- Create a smaller junior ADU
Each option presents different questions involving entrances, utilities, setbacks, construction costs, and available yard space. Clarifying your plan early makes it easier to determine whether the property is suitable.
Can the lot physically support the project?
A property may allow an ADU in theory but still be difficult or expensive to develop. Consider the lot’s shape, slope, drainage, existing structures, utility connections, easements, and access for construction crews and equipment.
Parking also deserves attention. Although many ADUs don’t require an additional space, parking requirements may apply to certain properties in the Coastal Overlay Zone’s Beach Impact Area unless an exception is available.
Which permits and approvals will be required?
A City of San Diego building permit is required to create an ADU or junior ADU. Coastal properties may also require a Coastal Development Permit, particularly when the project adds habitable space, converts non-habitable space, or isn’t fully contained within the existing primary residence.
Permit history matters as well. When buying a home in San Diego, confirm that any garage, addition, or other structure included in your plans was legally built and matches city records.
How do you intend to use the ADU?
Your intended use should be clear before you pay more for a property advertised as having “ADU potential.” An ADU may provide housing for relatives, generate longer-term rental income, or create more flexibility for future owners.
However, San Diego ADUs may not be leased for fewer than 31 consecutive days. Buyers shouldn’t assume a newly added unit can operate as a short-term vacation rental.
Evaluate the Property Before You Buy
Before making an offer based on ADU potential, consider having an architect, contractor, designer, or permit specialist complete a preliminary feasibility review.
RE/MAX COASTAL helps buyers buying a home in San Diego identify coastal properties that better align with their space, lifestyle, and long-term ownership plans.
Call 800.222.8281 or send us a message to explore your real estate opportunities in San Diego.